Helical guide channel with variable pitch

ABSTRACT

Disclosed embodiments include apparatuses, systems, and methods for guiding a rotatable actuator along a helical path with a varied pitch to motivate an attached implement. In an illustrative embodiment, an apparatus includes an elongated implement movable along an axis and a rotatable actuator operably coupled with a proximal end of the implement to motivate the implement to move along the axis in response to rotation of the rotatable actuator. A guide is operably coupled with rotatable actuator, where the guide defines a generally helical channel around the axis to direct movement of a rotatable actuator, and wherein a pitch of the helical channel is varied to reduce a distance of travel of the actuator along the axis per unit of rotation of the actuator.

PRIORITY CLAIM

The present application claims the priority and benefit of U.S.Provisional Patent Application Ser. No. 62/945,825 filed Dec. 9, 2019and entitled “USER INTERFACE AND LOCK FEATURES FOR POSITIONING MULTIPLECOMPONENTS WITHIN A BODY,” U.S. Provisional Patent Application Ser. No.62/945,836 filed Dec. 9, 2019 and entitled “HELICAL GUIDE CHANNEL WITHVARIABLE PITCH,” and U.S. Provisional Patent Application Ser. No.62/945,843 filed Dec. 9, 2019 and entitled “SLIDABLE COUPLING TO CONNECTDEVICES.”

FIELD

The present disclosure relates to a user interface and lock features forpositioning multiple components within a body.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Inserting and manipulating thin elements within living bodies or otherobjects allows for ever-improving types of analysis, diagnosis, andtreatment of those bodies or objects with minimally invasive techniques.By way of two examples, endoscopic imaging and catherization treatmentshave enabled evaluation and treatment of numerous internal lesionswithout invasive surgery.

Electrosurgical techniques also provide for minimally invasive therapiesby selectively applying electrical current to selected tissues.Electrosurgical techniques involve inserting one or more electrodesthrough an orifice or a small incision and then extending the one ormore electrodes to a desired location within a body of a patient. Aradio frequency (“RF”) electric current is then applied to theelectrodes to coagulate, ablate, or otherwise treat tissue at thatlocation. Monopolar electrosurgical instruments involve the insertion ofone electrode that electrically interacts with a second electrode thatis electrically connected to the body of the patient. A bipolarelectrosurgical instrument involves the deploying of two electrodes atthe location within the body of the patient where treatment is to beadministered.

Positioning one or two electrodes at the desired location in a patient'sbody is an important part of electrosurgical treatments. Moving andholding electrodes in place, particularly when more than one electrodehas to be moved or held independently of another electrode, may presenta challenge for medical personnel directing the treatment. Further,because positioning one or more electrodes in place may involvefollowing a particular sequence of steps in positioning the electrodes,assisting an operator in properly following the sequence also may beimportant.

SUMMARY

Disclosed embodiments include: apparatuses, systems, and methods forcontrolling the movement of multiple components within a body;apparatuses, systems, and methods for motivating elongated implementsusing a rotating actuator guided by a helical path of varying pitch; andapparatuses, systems, and methods for coupling a device, such as a userinterface for controlling movement of multiple components within a body,to another device.

In an illustrative embodiment, an apparatus includes an elongatedprimary electrode defining a lumen therein, an elongated secondaryelectrode slidably receivable within the lumen, and a sheath configuredto slidably receive the primary electrode therein, where the sheath isfurther configured to convey the primary electrode and the secondaryelectrode to a target region. A housing is operably coupled with thesheath and movably mounted to slidably motivate the sheath relative tothe target region. A primary actuator is operably coupled with theprimary electrode and slidably coupled with the housing to motivate theprimary electrode relative to the sheath. A secondary actuator isoperably coupled with the secondary electrode and movably coupled withthe primary actuator to be slidable with the primary actuator tomotivate the secondary electrode in concert with the primary electrode.The secondary actuator is rotatable independently of the primaryactuator to travel along a helical path to motivate the secondaryelectrode to move relative to the target region independently of theprimary electrode.

In another illustrative embodiment, a system for treating tissue at atarget region includes an electrical power source configured toselectively provide electrical power between a first pole and a secondpole via a two-pole electrical cable. An electrode control apparatusincludes an elongated primary electrode defining a lumen therein, anelongated secondary electrode slidably receivable within the lumen, anda sheath configured to slidably receive the primary electrode therein,where the sheath is further configured to convey the primary electrodeand the secondary electrode to a target region. A housing is operablycoupled with the sheath and movably mounted to slidably motivate thesheath relative to the target region. A primary actuator is operablycoupled with the primary electrode and slidably coupled with the housingto motivate the primary electrode relative to the sheath. A secondaryactuator is operably coupled with the secondary electrode and movablycoupled with the primary actuator to be slidable with the primaryactuator to motivate the secondary electrode in concert with the primaryelectrode. The secondary actuator is rotatable independently of theprimary actuator to travel along a helical path to motivate thesecondary electrode to move relative to the target region independentlyof the primary electrode.

In a further illustrative embodiment, a method includes moving a distalend of a sheath that contains a primary electrode and a secondaryelectrode adjacent to a target region. A primary actuator operablycoupled with the primary electrode and a secondary actuator operablycoupled to the secondary electrode and movably engaged with the primaryactuator are slid to a first position to motivate distal ends of theprimary electrode and the secondary electrode relative to the targetregion. The secondary actuator is rotated relative to the primaryactuator to cause the secondary actuator to travel independently of theprimary actuator along a helical path to a second position to motivatethe distal end of the secondary electrode to move independently of theprimary electrode relative to the target region.

In an additional illustrative embodiment, an apparatus includes anelongated implement movable along an axis. A rotatable actuator isoperably coupled with a proximal end of the implement to motivate theimplement to move along the axis in response to rotation of therotatable actuator. A guide is operably coupled with rotatable actuator,wherein the guide defines a generally helical path around the axis todirect movement of a rotatable actuator, and wherein a pitch of thehelical path is varied to reduce a distance of travel of the actuatoralong the axis per unit of rotation of the actuator.

In another additional illustrative embodiment, a system includes anelongated primary electrode defining a lumen therein. An elongatedsecondary electrode is slidably receivable within the lumen. A sheath isconfigured to slidably receive the primary electrode therein, the sheathbeing further configured to convey the primary electrode and thesecondary electrode toward a target region. A housing is operablycoupled with the sheath and movably mounted to slidably motivate thesheath relative to the target region. A primary actuator is operablycoupled with the primary electrode and slidably coupled with the housingto motivate the primary electrode to slide relative to the sheath alongan axis. The primary actuator includes a guide defining a generallyhelical path, wherein a pitch of the helical path is varied to reducemovement of a guide member relative to the axis per unit of rotation ofthe guide member around the helical path. A secondary actuator isoperably coupled with the secondary electrode and rotatably receivedwithin the guide of the primary actuator. The secondary actuatorsupports the guide member that is configured to engage the helical path.The secondary actuator is rotatable relative to the primary actuator tomotivate the secondary electrode to move relative to the primaryelectrode.

In a further additional illustrative embodiment, a method includescoupling an elongated implement at a proximal end thereof to an actuatorthat is movable along an axis. The implement is motivated by rotatablymoving the actuator through a generally helical path around the axis,where the helical path has a pitch that is varied to change a distancetraveled by the actuator along the axis per unit of rotation of theactuator.

In another additional embodiment, a locking body defines an opening witha first section having a first width and a second section having asecond width that is smaller than the first width, where the lockingbody is slidably mountable on one of a first device that supports afirst coupling and a second device that supports a second coupling. Oneof the first and second couplings is configured to support thereon aflange having a flange width that is smaller than the first width andlarger than the second width. A slidable mounting mechanism isconfigured to slidably secure the locking body on one of the firstdevice and the second device. The slidable mounting mechanism is furtherconfigured to enable the locking body to slide between an open position,in which the first section is positionable to enable the first couplingto be inserted into the second coupling to form a connection, and aclosed position, in which an edge of the locking body around the secondsection abuts the flange such that the coupling that supports the flangeis prevented from being withdrawn from the connection

In another additional illustrative embodiment, a system includes anelongated primary electrode defining a lumen therein. An elongatedsecondary electrode is slidably received within the lumen. A sheathslidably receives the primary electrode and is configured to convey theprimary electrode and the secondary electrode toward a target region. Ahousing is operably coupled with the sheath and is movably mounted toslidably motivate the sheath relative to the target region. A primaryactuator is operably coupled with the primary electrode and is movablycoupled with the housing to motivate the primary electrode relative tothe sheath. A secondary actuator is operably coupled with the secondelectrode and is movably coupled with the primary actuator, where thesecondary actuator is separately movable relative to the primaryactuator to motivate the secondary electrode to move relative to theprimary electrode. A first coupling is supported by the housing andconfigured to engage a second coupling supporting a flange having aflange width, where the second coupling extends from a device throughwhich the sheath and the electrodes will be conveyed to the targetregion. A locking body defines an opening having a first section havinga first width larger than the flange width and a second section having asecond width that is smaller than the flange width. A slidable mountingmechanism is configured to slidably secure the locking body to thehousing. The slidable mounting mechanism is further configured to enablethe locking body to slide between an open position, in which the firstsection is positionable to enable the first coupling to insertablyreceive the second coupling to form a connection, and a closed position,in which an edge of the locking body around the second section abuts theflange such that the coupling that supports the flange is prevented frombeing withdrawn from the connection.

In a further additional illustrative embodiment, a method includespositioning a locking body into an open position, where the locking bodydefines an opening with a first section having a first width and asecond section having a second width that is smaller than the firstwidth. The locking body is slidably mounted on one of a first devicethat supports a first coupling and a second device that supports asecond coupling. The first section is disposed between the firstcoupling and the second coupling when the locking body is positionedinto the open position. A connection is formed by inserting the firstcoupling within the second coupling such that one of the first andsecond couplings supports a flange having a flange width that is smallerthan the first width and larger than the second width. The locking bodyis repositioned into a closed position in which an edge of the lockingbody around the second section abuts the flange to prevent the flangefrom being withdrawn from the connection.

Further features, advantages, and areas of applicability will becomeapparent from the description provided herein. It should be understoodthat the description and specific examples are intended for purposes ofillustration only and are not intended to limit the scope of the presentdisclosure.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.The components in the figures are not necessarily to scale, withemphasis instead being placed upon illustrating the principles of thedisclosed embodiments. In the drawings:

FIG. 1 is a block diagram in partial schematic form of an illustrativesystem for treating tissue;

FIGS. 2-5 are schematic diagrams of positioning of distal ends of asheath, primary electrode, and secondary electrode relative to a targetregion;

FIGS. 6A and 7A are schematic diagrams of moving a sheath actuator toposition a sheath relative to the target region;

FIGS. 6B and 7B are schematic diagrams of distal ends of the sheath, aprimary electrode, and a secondary electrode relative to the targetregion corresponding to positions of the sheath actuator of FIGS. 6A and7A, respectively;

FIG. 8 is a side view of an illustrative sheath actuator and a sheathlock;

FIG. 9 is a cutaway view of the sheath actuator and sheath lock of FIG.8 ;

FIG. 10 is a side view of an embodiment of a user interface forpositioning components relative to the target region;

FIG. 11 is an exploded view of the user interface of FIG. 10 ;

FIGS. 12A, 13A, 14A, 15A, 16A, 17A, 18A, 19A, 20A, and 21A are sideviews of an embodiment of the user interface of FIG. 10 beingmanipulated to position multiple components relative to the targetregion;

FIGS. 12B, 13B, 14B, 15B, 16B, 17B, 18B, 19B, 20B, and 21B are schematicdiagrams of distal ends of the sheath, the primary electrode, and thesecondary electrode relative to the target region corresponding topositions of the user interface of FIGS. 12A, 13A, 14A, 15A, 16A, 17A,18A, 19A, 20A, and 21A, respectively;

FIG. 22 is a side view of a guide sleeve defining a helical channel ofvarying pitch for guiding a rotatable actuator;

FIG. 23 is a side view of sections of the guide sleeve of FIG. 22 ;

FIGS. 24 and 25 are side views of a wire having different cross-sectionsalong its length;

FIG. 26 is a cross-sectional view of the wire of FIGS. 24 and 25 ;

FIG. 27 is an exploded view of a coupler for joining together devices;

FIG. 28 is a side view of a locking body of the coupler of FIG. 27 ;

FIG. 29 is a flow diagram of an illustrative method of positioningcomponents using a user interface;

FIG. 30 is a flow diagram of an illustrative method of motivating animplement using a rotating actuator guided by a helical path of varyingpitch; and

FIG. 31 is a flow diagram of an illustrative method of coupling togetherdevices with a slidably-mounted locking body.

DETAILED DESCRIPTION

The following description is merely illustrative in nature and is notintended to limit the present disclosure, application, or uses. It willbe noted that the first digit of three-digit reference numbers and thefirst two digits of four-digit reference numbers correspond to the firstdigit of one-digit figure numbers and the first two digits of two-digitfigure numbers, respectively, in which the element first appears.

The following description explains, by way of illustration only and notof limitation, various embodiments of user interfaces to positionelectrodes for electrosurgical apparatuses, as well as systems includingsuch user interfaces and methods of using the same. As will be describedin detail below, electrosurgical techniques position first and secondelectrodes in a target region where electrical treatment, such asablative treatment, is to be applied. For a specific example, the userinterfaces and methods of their use may be used for ablating and/orcoagulating tissue, removing lesions, and for performing other medicalprocedures within a lung.

It will be appreciated that various embodiments of user interfacesdescribed herein may help to simplify the process of positioning theelectrodes and holding the electrodes in place. As will be describedbelow, various embodiments of the user interface accomplish theselective positioning and locking in place of the electrodes bydepressing a release, sliding one actuator, and rotating another.

Referring to FIG. 1 , a system 100 is provided for treating tissue at atarget region of a patient (not shown in FIG. 1 ). The system 100 may bea bipolar or monopolar radio frequency (RF) system, as desired, fortreating tissue in a patient. However, various embodiments describedherein are configured to position two electrodes at the target region tosupport implementation of a bipolar treatment system, thereby allowingfor electric current to be selectively passed through a particulartarget region in a patient. Specifically, the system 100 may be employedfor coagulation and/or ablation of soft tissue during percutaneousand/or endoscopic surgical procedures, such as, for example,bronchoscopic surgical procedures for partial and/or complete ablationof cancerous and/or noncancerous organ lesions. As will be furtherdescribed, the tissue is treated by positioning one or more electrodesproximate the tissue to be treated and passing an electrical currentthrough the tissue.

In some embodiments, the system 100 includes a user interface 102, anelectrosurgical radio frequency (RF) generator operating as a switchablecurrent source 114, an infusion pump 116, and an electrosurgicalinstrument or device 118, such as, without limitation, a bronchoscope orany other electrosurgical or endoscopic instrument as desired for aparticular application. The user interface 102 may be joined with theelectrosurgical apparatus 118 with a coupler 150. The electrosurgicalapparatus 118 may be used to convey electrodes (not shown in FIG. 1 )through a sheath 103 where the user interface 102 may be used tomanipulate positions of the electrodes at the target region.

The user interface 102 electrically communicates with the switchablecurrent source 114 though an electrical conductor 130. In someembodiments, the electrical conductor 130 is connected to a bipolaroutlet 131 on the switchable current source 114 when the system isoperated in a bipolar mode. The electrical conductor 130 may be coupledwith the outlet 131 using an electrical connector 134 configured toelectrically engage the outlet 131. The electrical conductor 130 may beremovably or fixably coupled to the user interface 102, where a flexibleelectrical coupling (not shown in FIG. 1 ) associated with the userinterface 102 electrically couples the current to the electrodes, asfurther described below with reference to FIG. 11 . In some otherembodiments, the system 100 can be operated in a monopolar mode when theelectrical conductor 130 is connected to a secondary outlet 133 with anadapter (not shown in FIG. 1 ).

The user interface 102 is further connected to the infusion pump 116with a tube 132 that facilitates the flow of a conductive fluid, such assaline solution, from the infusion pump 116 to the user interface 101.As also described below with reference to FIG. 11 , the user interface102 may include a flexible fluid coupling (not shown in FIG. 1 ) thatreceives the flow of conductive fluid from the infusion pump 116 anddelivers the conductive fluid to an interior of a primary electrodewhere it can be delivered to the target region.

The switchable current source 114 may be operated with the use of a footoperated unit 120 electrically connected to the switchable currentsource 114. The foot operated unit 120 may include a pedal 122 thatdirects the switchable current source 114 to apply an electrical currentto one or more electrodes to cut, ablate, or otherwise treat tissue anda pedal 124 that instructs the switchable current source 114 to apply alower electrical current to the one or more electrodes to coagulatetissue.

In various embodiments the electrosurgical apparatus 118 includes aninsertion tube 119 that permits insertion of the sheath 103 into a body(not shown) through an orifice or an incision. A distal end 105 of thesheath 103 is delivered to a target region where treatment is to beadministered. The sheath 103 contains and conveys the electrodes (notshown) to a desired treatment location. Positioning of the distal end105 of the sheath 103 and the distal ends of the electrodes (not shownin FIG. 1 ) may be controlled by the user interface 102 received by theelectrosurgical apparatus 118 as further described below with referenceto FIGS. 6A-21B.

Referring to FIGS. 2-5 , distal ends of components used to administertreatment are positioned relative to a target region 202 using variousembodiments of a user interface 102. The target region 202, may includea lesion or any portion of tissue to be treated within a body. Variousembodiments of the user interface 102 described below are capable ofpositioning the components as described with reference to FIGS. 2-5 andas further described with reference to FIGS. 6A-21B. The description ofFIGS. 2-5 is provided as a baseline to describe an application withwhich various embodiments of the user interface 102 may be used todeploy these components.

In various embodiments, a secondary electrode 211 is slidably receivedwithin a primary electrode 207, and the primary electrode 207 isslidably received within a sheath 203. Components contained within othercomponents are represented with dashed lines in FIGS. 2-5 . In variousembodiments, the primary electrode 207 is in the form of a needle, withthe distal end 209 being configured to pierce tissue, such as tissuecomprising the target region 202. Piercing the tissue at the targetregion 202 with the primary electrode facilitates positioning the distalend 209 of the primary electrode 207 at a desired position and alsofacilitates conveying the secondary electrode 211 to a desired location.In various embodiments, until a user interface is manipulated toseparately move the secondary electrode 211, the primary electrode 207and the secondary electrode 211 move in concert, at a same time andthrough a same distance, with each other and with the sheath 203.

Referring to FIG. 2 , the sheath 103, the primary electrode 207, and thesecondary electrode 211 are positioned at an initial position near thetarget region 202. The sheath 103 and the electrodes 207 and 211received therein may be conveyed to this location through the use of abronchoscope or other electrosurgical device 118, as previouslydescribed with reference to FIG. 1 . A distal end 105 of the sheath 103is positioned in the vicinity of the target region 202. The primaryelectrode 207 is slidably received within the sheath 103, with a distalend 209 of the primary electrode 207 at or near the distal end 105 ofthe sheath 103. Specifically, FIG. 2 , for example, shows the distal end209 of the primary electrode 207 positioned just short of the distal end105 of the sheath 103. In turn, the secondary electrode 211 is slidablyreceived within the primary electrode 207, with the distal end 213 ofthe secondary electrode 211 positioned just within the distal end 209 ofthe primary electrode 207.

Referring to FIG. 3 , the sheath 103, the primary electrode 207, and thesecondary electrode 211 are positioned once the sheath 103 has beenmoved closer to the target region 202. The sheath 103 may be movedtoward the target region 202 using a sheath actuator, as described belowwith reference to FIGS. 6A-7B. As contrasted with FIG. 2 , in FIG. 3 ,the distal end 105 of the sheath 103 has been moved closer to the targetregion 202. Because the primary electrode 207 and the secondaryelectrode 211 have not been separately moved through the manipulation ofa user interface (not shown), the primary electrode 207 and thesecondary electrode 211 have moved in concert with the sheath 103,traveling a same distance in a same direction as the sheath 103. Thedistal end 209 of the primary electrode 207 remains positioned justshort of the distal end 105 of the sheath 103, and the distal end 213 ofthe secondary electrode 211 remains positioned just within the distalend 209 of the primary electrode 207.

Referring to FIG. 4 , the sheath 103, the primary electrode 207, and thesecondary electrode 211 are positioned once the primary electrode 207has been extended from the sheath 103 into the target region 202. Invarious embodiments, the secondary electrode 211 moves in concert withthe primary electrode 207 as the primary electrode 207 is extendedbeyond the distal end 105 of the sheath 103. Thus, the secondaryelectrode 211 moves in the same direction and moves through the samedistance as the primary electrode 207, as shown in FIG. 4 . The distalend 213 of the secondary electrode 211 remains positioned just withinthe distal end 209 of the primary electrode 207.

Referring to FIG. 5 , the sheath 103, the primary electrode 207, and thesecondary electrode 211 are positioned once the secondary electrode 211has been extended from the primary electrode 207. A distal end 213 ofthe secondary electrode 211 is deployed at a position across the targetregion 202 from the primary electrode 207. In particular embodiments,the secondary electrode 211 is configured as a coilable wire which isconstrained within the primary electrode 207 in a straightened form. Thesecondary electrode 211 may be formed of an alloy, such as nitinol, anickel-titanium allow, or other “memory” alloy to regain a certain shapeafter being released from a confined position. Once the user interface102 (not shown in FIG. 5 ) is manipulated to independently extend thesecondary electrode 211 from the primary electrode 207, a portion of thesecondary electrode 211 coils. As a result, the distal end 213 of thesecondary electrode 211 augers into tissue at the target region 202. Theaugering of the distal end 213 of the secondary electrode 211 may assistin securing the position of the distal end 213 of the secondaryelectrode 211 during treatment.

Still referring to FIG. 5 , an insulated section 515 of the secondaryelectrode 211 stops short of the distal end 213 of the secondaryelectrode 211. The insulation 515 electrically insulates the secondaryelectrode 211 from the primary electrode 207 such that, when electricalcurrent is applied to proximal ends (not shown) of the primary electrode207 and the secondary electrode 211, the electrical current may onlyflow between the distal end 209 of the primary electrode 207 and theuninsulated distal end 213 of the secondary electrode 211.

As will be further described below, various embodiments of the userinterface 102 facilitate moving the primary electrode 207 and thesecondary electrode 211 in concert with the sheath 103 as the sheath ispositioned adjacent the target region 202, as described with referenceto FIG. 3 . Various embodiments of the user interface also facilitatemoving the primary electrode 207 and the secondary electrode 211 inconcert as they are extended beyond the distal end 105 of the sheath103, as described with reference to FIG. 4 . To this end, variousembodiments of the user interface 102 may prevent moving the secondaryelectrode 211 independently of the primary electrode 207 until theprimary electrode 207 is extended beyond the distal end 105 of thesheath 103. Once the primary electrode 207 has been extended, variousembodiments of the user interface facilitate moving the secondaryelectrode 211 independently of the primary electrode 207 to permitseparate positioning of the secondary electrode, as described withreference to FIG. 5 . Further, once the primary electrode 207 isdeployed at a desirable position, various embodiments of the userinterface may prevent the primary electrode 207 from being moved whilethe secondary electrode 211 is being separately deployed and/or once thesecondary electrode 211 has been situated at a desired location.Embodiments of a user interface 102 to coordinate movements of thesheath 103 and electrodes 207 and 211 is explained below with referenceto FIGS. 6A-20 .

Referring to FIGS. 6A and 6B, the user interface 102 includes a sheathactuator 604 that is used to position the distal end 105 of the sheath103, as previously described with reference to FIG. 3 . The userinterface 102 is joined with the electrosurgical apparatus 118 with thecoupler 150, as previously described with reference to FIG. 1 . Theelectrosurgical apparatus 118, such as a bronchoscope or anotherminimally invasive device used for performing diagnostic or therapeutictasks, conveys the sheath 103 into the body (not shown in FIGS. 6A and6B) near the target region 202.

Again referring to FIG. 6A, the user interface 102 includes a sheathactuator 604 and a sheath lock 606 configured to move the sheath 103 toposition the distal end 105 of the sheath 103 at a desired locationrelative to a target region 202. In some embodiments, the sheathactuator 604 may be a slidable mechanism incorporating a slidable sleeve612. At one end, the slidable sleeve 612 is slidably received within acollar 614 at an end of a housing 610 of the user interface 102. At anopposing end, the slidable sleeve 612 is joined with the coupler 150.The slidable sleeve 612 may be locked in position at the collar 614 bythe sheath lock 606. The sheath lock 606 may include a thumbscrew, aspring-loaded locking pin, or another mechanism configured tomechanically engage the slidable sleeve 612 to secure the slidablesleeve 612—and, in turn, the sheath 103—in place at a desired location.In some other embodiments, the sheath actuator 604 may, for example, bepart of the electrosurgical apparatus 118. Any such embodiments of thesheath actuator 604 may facilitate movement of the sheath 103, asfurther described below.

Referring to FIG. 6B, before engaging the sheath actuator 604 to extendthe sheath 103, the sheath 103 and the primary electrode 207 and thesecondary electrode 211 received therein are positioned near the targetregion 202, as shown in FIG. 2 .

Referring to FIGS. 7A and 7B, manipulation of the sheath actuator 604illustrates an example of how the sheath 103 may be unlocked and movedinto position as previously described with reference to FIG. 3 . In theconfiguration shown in FIGS. 7A and 7B, the sheath actuator 604 has beenmanipulated to enable the sheath 103 to be moved a distance 719 closerto the target region 202. Specifically, the sheath lock 606 of thesheath actuator 604 is released to enable movement of the slidablesleeve 612 within the collar 614. Then, the housing 610 of the userinterface 102 is moved a distance 719 relative to the electrosurgicaldevice 118 to move the sheath 103 the same distance 719 toward thetarget region 702. Once the distal end 105 of the sheath 103 has reachedthe desired location relative to the target region 202, the slidablesleeve 612 may be locked in position at the collar 614 by the sheathlock 606. In various embodiments of the user interface 102, theelectrodes 207 and 211 move with the housing 610, so that when thehousing 610 is moved to reposition the sheath 103, the electrodes 207and 211 move in concert with the sheath 103. Therefore, as shown in FIG.7B, while the distal end 105 of the sheath 103 is advanced toward thetarget region 202, the electrodes 207 and 211 move with the sheath 203.As in FIG. 6B, the distal end 209 of the primary electrode 207 remainswithin the distal end 105 of the sheath 103 and the distal end 213 ofthe secondary electrode 211 remains within the distal end 209 of theprimary electrode 207.

Referring to FIG. 8 , in an illustrative sheath actuator 604 and asheath lock 606 the slidable sleeve 612 is slidably received within thecollar 614 of the housing 610. The slidable sleeve 612 is fixablyattached to the coupler 150 that engages the user interface 102 with theelectrosurgical apparatus (not shown in FIG. 8 ). The sheath lock 606 inthe embodiment of FIG. 8 is a thumbscrew that may be loosened to permitmovement of the collar 614 fixably attached to the coupler 150 to movethe sheath (not shown in FIG. 8 ) as previously described with referenceto FIGS. 6A-7B. After the housing 610 has been manipulated to slide thecollar 614 relative to the slidable sleeve 612 to move the distal end105 of the sheath 103 to a desired location, such as described withreference to FIG. 7B, the sheath lock 606 is reengaged, such as byturning a thumbscrew, to fix the position of the sheath.

Referring to FIG. 9 , the sheath 103 and the electrodes 207 and 211extend through the slidable sleeve 612. As a result, movement of thehousing 610, to which the sheath 103 and the electrodes 207 and 211 areoperably coupled, results in movement of the sheath 103 and theelectrodes 207 and 211. A distal end 907 of the sheath lock 606 thatextends through the collar 614 mechanically engages the slidable sleeve612 to control movement of the slidable sleeve 612. Releasing the sheathlock 606, such as by loosening a thumb screw, permits the slidablesleeve 612 to be slidably moved relative to the collar 614 by moving thehousing 610, as described with reference to FIG. 7A. Securing the sheathlock 606, such as by tightening the thumbscrew, mechanically secures theslidable sleeve 612 in place relative to the collar 614, preventingfurther movement of the slidable sleeve 612, thereby securing the distalend 105 of the sheath 103 in place.

Referring to FIG. 10 , in various embodiments, the user interface 102includes control surfaces for positioning the sheath 103 and theelectrodes 207 and 211 (none of which are shown in FIG. 10 ). The userinterface 102 includes the housing 610 that supports components that aremoved parallel along an axis 1001 or that are rotated along a curve 1003around the axis 1001, as further described below. The user interface 102includes the sheath actuator 604, including the collar 614 that receivesthe slidable sleeve 612 (fully received within the collar 614 and, thus,not shown in FIG. 10 ) and the sheath lock 606. The sheath actuator 604joins the housing 610 to the coupler 150 which, in turn, couples theuser interface 102 with an electrosurgical device (not shown in FIG. 10). As further described in more detail below, the user interface 102includes a primary actuator 1010, which controls movement of the primaryelectrode 207 (not shown in FIG. 10 ), and a secondary actuator 1020,which controls movement of the secondary electrode 211 (not shown inFIG. 10 ).

The primary actuator 1010 includes a depressible actuator lock 1012 thatextends through an actuator opening 1014 in the primary actuator 1010.The primary actuator 1010 is slidably engaged with the housing 610. Theactuator lock 1012 is hingably or flexibly mounted on the primaryactuator 1010. Depressing the actuator lock 1012 partially moves theactuator lock 1012 through the actuator opening 1014 and a correspondingopening or recess (not shown in FIG. 10 ) in the housing 610 todisengage the primary actuator 1010 from the housing 610. As a result,depressing the actuator lock 1012 permits the primary actuator 1010 toslide along the axis 1001, as further described below. The secondaryactuator 1020 includes an actuator knob 1022 that is engageable torotate the secondary actuator 1020 through the curve 1003 around theaxis 1001, as also further described below. As also further describedbelow, in various embodiments, actuator interlocks restrict movement ofthe secondary actuator 1020 until the primary actuator 1010 is moved toextend the primary electrode 207 (not shown in FIG. 10 ), and restrictmovement of the primary actuator 1010 once the secondary actuator 1020is moved to extend the secondary electrode 211.

Referring to FIG. 11 , various components of the user interface 102,including portions of the housing 610, the primary actuator 1010, andthe secondary actuator 1020 illustrate the interrelationship of thecomponents in various embodiments. The housing 610 (FIG. 10 ) includes afirst housing section 1131 and a second housing section 1133. Thehousing sections 1131 and 1133 have hollow interiors to receive andpermit movements of other components arranged therein. A first housingsection 1131 internally supports a locking rack 1128 that engages theactuator lock 1012. More specifically, the locking rack 1128 includesrecesses having openings facing inwardly into the housing 610 to permitselective engagement with the actuator lock 1012. The second housingsection 1133 also may include a depth scale 1134 that may be used tovisually gauge a position of the primary electrode 207 based on aposition of the primary actuator 1010 relative to the housing 610. Asecond housing section 1133 threadably supports the sheath lock 606,which is part of the sheath actuator 604, as previously described withreference to FIGS. 6A-9 . The housing sections 1131 and 1133 are matablesections, joinable by adhesives or fasteners, such as screws (not shownin FIG. 11 ).

In various embodiments, primary actuator sections 1111 and 1113 areslidably received around the housing section 1131 and 1133. The primaryactuator sections 1111 and 1113 are have generally hollow interiors toslidably receive the housing sections 1131 and 1133 therebetween. Afirst primary actuator section 1111 defines the actuator opening 1014that receives the actuator lock 1012. The actuator lock 1012 has a base1124 that is fixably securable to the first primary actuator section1111 and around which the actuator lock 1012 partially rotates into anopening or recess (not shown in FIG. 11 ) in the housing 610 when theactuator lock 1012 is depressed. At an end opposite the base 1124, theactuator lock 1012 also supports a pin support 1126 that holds a pin1127 that engages the locking rack 1128 of the first housing section1131 when the actuator lock 1012 is not depressed.

In various embodiments, the actuator lock 1012 is biased into a lockingposition where the pin support 1126 causes the pin 1127 to engage thelocking rack 1128 when the actuator lock 1012 is released. The actuatorlock 1012 may be biased by rigidity of the actuator lock 1012 causingthe actuator lock 1012 to resume its undeformed position when theactuator lock 1012 is released. Alternatively, the actuator lock 1012may be spring loaded by a spring actuator (not shown) positioned betweenthe actuator lock 1012 and the housing 610. The primary actuatorsections 1111 and 1113 are joinable by adhesives or fasteners, such asscrews (not shown in FIG. 11 ).

Another portion of the primary actuator 1010 is a secondary actuatorguide, comprised of guide sections 1151 and 1153 couplable to theprimary actuator sections 1111 and 1113. As described in more detailwith reference to FIGS. 22 and 23 , the guide sections 1151 and 1153 arejoinable at their ends to form an annular tube and, between theirrespective edges, define a helical channel that receive guide members1136 and 1138 extending outwardly from secondary actuator sections 1121and 1123. The engagement of the guide members 1136 and 1138 with thehelical channel defined by edges of the guide sections 1151 and 1153,with reference to FIG. 10 , cause the secondary actuator 1020 to advancealong the axis 1001 when the secondary actuator 1020 is rotated througha curve 1003 around the axis 1001.

In various embodiments, secondary actuator sections 1121 and 1123 arerotatably mounted between the housing sections 1131 and 1133. Thesecondary actuator sections 1121 and 1123 are generally hollow toreceive therebetween other components of the user interface 102. Aspreviously described, each of the secondary actuator sections 1121 and1123 outwardly support the guide members 1136 and 1138 that engage thehelical channel defined by edges of the guide sections 1151 and 1153.Ends 1129 and 1139 of the respective secondary actuator sections 1121and 1123 are shaped to engage the actuator knob 1022 used to rotate thesecondary actuator 1020, as will be further described below withreference to FIGS. 16A and 17A. The secondary actuator sections 1121 and1123 are joinable by adhesives or fasteners, such as screws (not shownin FIG. 11 ).

In various embodiments, the primary actuator 1010 and the secondaryactuator 1020 include actuator interlocks to control relative movementof the actuators 1010 and 1020. In various embodiments, a firstsecondary actuator half 1121 may support a recess 1137 and a lockingmember 1139 to control relative movements of the primary actuator 1010and the secondary actuator 1020. The recess 1137 may be configured toreceive the pin support 1126 extending from the actuator lock 1012 toenable the actuator lock 1012 to be depressed to advance the primaryactuator 1010. However, after the primary actuator 1010 is moved, theactuator lock 1012 is released, and the secondary actuator 1020 isrotated, the rotation of the secondary actuator 1020 results in therecess 1137 being displaced from under the pin support 1126. As a resultof the displacement, the actuator lock 1012 is no longer depressiblebecause a body of the secondary actuator 1020 blocks the pin support1126, thereby preventing depressing of the actuator lock 1012. However,after the secondary actuator 1020 is returned to its starting position,the recess 1137 again rotates beneath the pin support 1126, allowingdepressing of the actuator lock 1012 to permit movement of the primaryactuator 1010.

Similarly, to prevent rotation of the secondary actuator 1020 before theprimary actuator 1010 is moved to deploy the primary electrode 207, thelocking member 1139 may engage a notch (not shown) in the housing 610.After the actuator lock 1012 is depressed and the primary actuator 1010is moved relative to the housing 610 to deploy the primary electrode207, the locking member 1139 clears the housing 610. It should be notedthat the recess 1137 will continue to receive the pin support 1126 aslong as the actuator lock 1012 is depressed, continuing to preventrotation of the secondary actuator 1020. Once the actuator lock 1012 isdisengaged, the secondary actuator 1020 is rotatable to deploy thesecondary electrode 211 and to block the actuator lock 1012 from beingengaged to permit movement of the primary actuator 1010. Thus, in sum,the actuator interlocks ensure that the primary actuator 1010 be movedto deploy the primary electrode 207 before the secondary actuator 1020may be rotated. Then, once the primary actuator 1010 has been moved todeploy the primary electrode 207 and the secondary actuator 1020 isrotated from its starting position, the actuator interlocks prevent theprimary actuator 1010 and the primary electrode 207 from being moveduntil the secondary actuator 1020 is moved to retract the secondaryelectrode 211 to its original position.

The user interface 102 also includes a sheath mount 1135 that isreceivable between the housing sections 1131 and 1133 to mechanicallyengage the housing 610 with the sheath 103. As a result, as describedwith reference to FIGS. 6A-9 , movement of the housing 610 extends orretracts the sheath 103. The user interface also includes electrodesliders coupled with the respective electrodes 207 and 211. A primaryelectrode slider 1145 is mechanically engageable by the primary actuatorsections 1113 and 1133 so that sliding the primary actuator 1010advances or retracts the primary electrode slider 1145 to advance orretract the primary electrode 207, respectively. A secondary electrodeslider (not shown in FIG. 11 ) mechanically engageable by the secondaryactuator sections 1121 and 1123 is slidably received within the primaryelectrode slider 1145. Because the secondary actuator sections 1121 and1123 are rotatably moved, as further described below, the secondaryelectrode slider is also rotatably received between the secondaryactuator sections 1121 and 1123.

A flexible wiring harness 1150 is configured to receive one or moreconductors of the electrical conductor 130 (FIG. 1 ) at a port on thehousing 610 (not shown in FIG. 11 ), and to electrically connect withflexible leads 1152 and 1154, each of which connects with one of theelectrodes 207 and 211. The flexible leads 1152 and 1154 are configuredto remain electrically connected with the electrodes 207 and 211 asproximal ends of the electrodes 207 and 211 are moved within the userinterface 102.

Additionally, a flexible fluid coupling 1160 extends from a fluid port(not shown in FIG. 11 ) on the housing 610 to an interior of the primaryelectrode slider 1145 to convey fluid into a lumen defined within theprimary electrode 207. The fluid port receives the tube 132 from theinfusion pump 116 (FIG. 1 ) at the housing 610 to receive a flow ofconductive fluid. The flexible fluid coupling 1160 may be coiled withinthe housing 610 to permit extension and contraction of the fluidcoupling 1160 with the movement of the primary electrode slider 1145relative to the housing 610.

As further described below with reference to FIGS. 27 and 28 , thecoupler 150 includes a slidable locking body 1180 that is slidablyreceived between a slidable mount 1182 and a retaining ring 1184. Theslidable mount 1182 is coupled with the housing 610. As furtherdescribed below, once the housing 610 is positioned to engage theelectrosurgical device 118 (not shown in FIG. 11 ), the locking body1180 is slid into place to secure the connection, as further describedwith reference to FIGS. 27 and 28 .

Referring to FIGS. 12A-21B, operation of the user interface 102 andcorresponding movements of the sheath 103, the primary electrode 207,and the secondary electrode 211 are described.

Referring to FIGS. 12A and 12B, the distal end 105 of the sheath 103 ispositioned adjacent to the target region 202. As previously describedwith reference to FIGS. 6A-7B, in various embodiments, the sheathactuator 604 enables the sheath 103 to be positioned by releasing thesheath lock 606 and moving the housing 610. For example, referring againto FIGS. 6A-7B, a position of the sheath 103 is controlled by slidingthe slidable sleeve 612 within the collar 614, then securing the sheath103 at the desired location by reengaging the sheath lock 606. When thedistal end 105 of the sheath 103 is deployed adjacent to the targetregion 202, a distal end 209 of the primary electrode 207 lies justwithin the distal end 105 of the sheath 103. At the same time, thedistal end 213 of the secondary electrode 211 lies just within thedistal end 209 of the primary electrode 207. With the distal end 105 ofthe sheath 103 positioned adjacent the target region 202, the userinterface 102 may be used to move the electrodes 207 and 211 to desiredpositions.

Referring to FIGS. 13A and 13B, according to various embodiments,positioning the electrodes 207 and 211 begins with depressing theactuator lock 1012 to enable movement of the primary actuator 1010.Depressing the actuator lock 1012 to move the actuator release 1012 in adirection 1301 disengages the primary actuator 1010 from the housing610. Specifically, depressing the actuator lock 1012, which is hingablyor rotatably coupled with the primary actuator 1010 at the base 1124,causes the pin support 1126 to move the pin 1127 from inward-facingrecesses of the locking rack 1128 on the housing 610. With the pin 1127removed from the locking rack 1128, the primary actuator 1010 is movablerelative to the housing 610 to move the primary electrode 207, asdescribed with reference to FIGS. 14A and 14B.

As previously described, the secondary actuator 1020 is rotatablyengaged with the primary actuator 1010. Accordingly, the secondaryactuator 1020 remains engaged with the primary actuator 1010 even whenthe actuator lock 1012 is released to release the primary actuator 1010from the housing 610. Therefore, depressing the actuator lock 1012 freesthe primary actuator 1010 and the secondary actuator 1020 to movecollectively, thus enabling the primary electrode 207 and the secondaryelectrode 211 to be moved collectively.

Referring to FIGS. 14A and 14B, while a user continues to depress theactuator lock 1012 in the direction 1301, the primary actuator 1010 ismoved in a direction 1401. Because the secondary actuator 1020 remains(rotatably) engaged with the primary actuator 1010 as previouslydescribed, the primary actuator 1010 and the secondary actuator movecollectively the same distance in the direction 1401, as represented inFIG. 14A.

As a result of the collective movement of the primary actuator 1010 andthe secondary actuator 1020, the primary electrode 207 and the secondaryelectrode 211 move collectively as well. Thus, as depicted in FIG. 14B,the distal end 209 of the primary electrode 207 and the distal end 213of the secondary electrode 211 move collectively beyond the distal end105 of the sheath 103 into the target region 202. Thus, by virtue of theengagement of the secondary actuator 1020 with the primary actuator1010, depressing the actuator lock 1012 and moving the primary actuator1010 moves both electrodes 207 and 211 collectively.

As previously described with reference to FIG. 11 , with the actuatorlock 1012 depressed, in various embodiments, the pin support 1026 on theactuator release 1012 engages the secondary actuator 1020, preventingthe secondary actuator 1020 from being rotated until the actuatorrelease 1012 is disengaged. As also previously described, the secondaryactuator 1020 may include the locking member 1139 that abuts the housing610. This arrangement prevents the secondary actuator 1020 from beingrotated before the actuator lock 1012 is depressed and the primaryactuator 1010 and the secondary actuator 1020 are advanced.

Referring to FIGS. 15A and 15B, once the distal ends 209 and 213 of theprimary electrode 207 and the secondary electrode 211, respectively,have been advanced into the target region 202, the actuator lock 1012 isreleased. Because the actuator lock 1012 is biased by its rigidity or bya spring, as described with reference to FIG. 11 , releasing theactuator lock 1012 results in the actuator lock 1012 moving in adirection 1501. The movement of the actuator lock 1012 causes theprimary actuator 1010—and the rotatably engaged secondary actuator1020—to again be engaged with the housing 610, holding the electrodes207 and 211 in place. As described with reference to FIG. 11 , when theactuator lock 1012 is released, a pin 1127 mounted in the pin support1026 moves into recesses in the locking rack 1128 mounted on the housing610. Thus, the engagement of the pin 1127 with the locking rack 1128prevents further movement of the primary actuator 1010 until theactuator lock 1012 is further engaged by a user. Accordingly, with theuser releasing the actuator lock 1012, the distal ends 209 and 213 ofthe primary electrode 207 and the secondary electrode 211 are secured inthe locations to which they were moved as described with reference toFIGS. 14A and 14B.

Referring to FIGS. 16A and 16B, with the primary actuator 1010 held inplace by the user's release of the actuator lock 1012, the secondaryactuator 1020 is rotated to move the secondary electrode 211independently of the primary electrode 207. As shown in FIG. 16A, thesecondary actuator 1020 is moved by a user rotating the actuator knob1022 in a direction 1601. As previously described with reference to FIG.11 , the secondary actuator 1020 supports guide members 1136 and 1138that are received within the helical channel defined between edges ofthe guide sections 1151 and 1153. With the secondary actuator 1020engaged with the helical channel defined by the guide sections 1151 and1153, rotation of the actuator knob 1022 results in helical movement ofthe secondary actuator 1020. The rotation of the secondary actuator 1020thus causes the secondary actuator 1020 to advance in a direction 1602relative to the primary actuator 1010 and the housing 610.

Referring to FIG. 16B, movement of the secondary actuator 1020 resultsin the distal end 213 of the secondary electrode 211 extending beyondthe distal end 207 of the primary electrode 209. As previously describedwith reference to FIG. 5 , the distal end 213 of the secondary electrode211 may be preformed into a coiled shape, thereby resulting in thesecondary electrode 211 forming a coiled shape once the secondaryelectrode 211 is no longer constrained within the lumen of the primaryelectrode 207. In various embodiments, the coiled shape at the distalend 213 of the secondary electrode 211 augers into the tissue of thetarget region 202, which secures the secondary electrode 211—and theprimary electrode 207 through which it extends—in position at the targetregion 202. The insulated section 515 of the secondary electrode 211electrically insulates the secondary electrode 211 from the primaryelectrode 207 except as between their respective distal ends 213 and209. With the distal ends 213 and 209 of the electrodes 211 and 207deployed, a supply of conductive fluid and/or electrical current may beapplied to the target region 202 as previously described to effecttreatment.

The actuator interlocks presented by the configuration of the actuators1010 and 1020 prevent the user from moving the primary actuator 1010once the secondary actuator 1020 is rotated from its original position.As previously described with reference to FIG. 11 , rotating thesecondary actuator 1020 blocks the pin support 1126 of the actuator lock1012, thereby preventing a user from depressing the actuator lock 1012to release the primary actuator 1010 from its engagement with thehousing 610 via the pin 1127 and the locking rack 1128. Thus, the distalend 209 of the primary electrode 207 remains in place as inserted intothe target region 202 while the secondary actuator 1020 is moved toextend the distal end 213 of the secondary electrode 211 into the targetregion 202.

Deployment of the sheath 103 and the electrodes 207 and 211 to permitthe application of treatment is described with reference to FIGS. 6A-7Band 12A-16B. Conversely, to withdraw and move the electrodes 207 and 211from the target region 202, manipulations and the sequence ofmanipulations of the user interface 102 is reversed, as described withreference to FIGS. 17A-21B.

Referring to FIGS. 17A and 17B, the distal end 213 of the secondaryelectrode 211 is retracted into the primary electrode 207 by a userrotating the actuator knob 1022 in a direction 1701. The direction 1701in which the actuator knob 1022 is rotated to retract the distal end 213of the secondary electrode 211 from the target region 202 is opposite tothe direction 1601 in which the actuator knob 1022 was rotated to extendthe distal end 213 of the secondary electrode 211. Rotation of theactuator knob 1022 results in an opposite, helical movement of thesecondary actuator 1020, resulting the secondary actuator 1020translating in a direction 1702 relative to the primary actuator 1010and the housing 610. The movement of the secondary actuator 1020withdraws the secondary electrode 211 until the distal end 213 of thesecondary electrode 211 again is received within the distal end 209 ofthe primary electrode 207. With the secondary actuator 1020 moved to itsoriginal position relative to the primary actuator 1010, the actuatorlock 1012 now may be released, as described with reference to FIG. 18A.It will be appreciated that retraction of the secondary electrode 211 isaccomplished by rotating the secondary actuator 1020 while the primaryactuator 1010 remains stationary.

Referring to FIGS. 18A and 18B, to prepare for retraction of the primaryelectrode 207 from the target region 202, the actuator lock 1012 isdepressed by a user in a direction 1801. Depressing the actuator lock1012 does not result in any movement of the distal ends 209 and 213 ofthe electrodes 207 and 211, respectively, just as engagement of theactuator lock 1012 did not result in movement of the electrodes 207 and211 when the actuator lock 1012 was depressed and released as previouslydescribed with reference to FIGS. 13A and 13B and FIGS. 15A and 15B,respectively.

Referring to FIGS. 19A and 19B, with the actuator lock 1012 depressed,the primary actuator 1010 is moved in a direction 1901 to withdraw thedistal end 209 of the primary electrode 207 from the target region 202.As previously described with reference to FIGS. 14A and 14B, because thesecondary actuator 1020 remains rotationally engaged with the primaryactuator 1010, the secondary actuator 1020 also moves a same distanceand in the same direction 1901 as the primary actuator 1010. As aresult, the distal ends 209 and 213 of the electrodes 207 and 211 aremoved collectively and withdrawn from the target region 202. After theprimary actuator 1010 is fully retracted in the direction 1901, thedistal end 209 of the primary electrode 207 is received within thedistal end 105 of the sheath. Further, because the secondary actuator1020—and, thus, the secondary electrode 211—moves in concert with theprimary actuator 1010, the distal end 213 of the secondary electrode 211remains within the distal end 209 of the primary electrode 207 as thedistal end 209 of the primary electrode 207 is withdrawn within thedistal end 105 of the sheath 103.

Referring to FIGS. 20A and 20B, once the distal ends 209 and 213 of theelectrodes 207 and 211, respectively, are withdrawn within the distalend 105 of the sheath 103, the actuator lock 1012 is released. Uponrelease of the actuator lock 1012, the actuator lock 1012 moves in adirection 2001. As a result, the pin 1127 held by the pin support 1126reengages the locking rack 1128 to hold the primary actuator 1010 inplace. Further, as previously described, the actuator interlocks thatprevent the secondary actuator 1020 from being rotated, such as by thelocking member 1139 extending from the secondary actuator 1020 engagingthe housing 610, prevents rotation of the secondary actuator 1020 whilethe actuators 1010 and 1020 have resumed a starting position asdescribed with reference to FIGS. 12A and 12B.

Referring to FIGS. 21A and 21B, with distal ends 209 and 211 of theelectrodes 207 and 211, respectively, withdrawn within the distal end105 of the sheath 103, the sheath 103 itself may be withdrawn. In anoperation opposite that depicted in FIGS. 7A and 7B, the sheath lock 606is released and the housing 610 is moved along the slidable sleeve 612in a direction 2101 away from the coupling 150. Because the primaryactuator 1010 is locked to the housing by the actuator lock 1012, andthe secondary actuator 1020 is rotatably secured to the primary actuator1010, the primary actuator 1010 and the secondary actuator 1020 move inconcert with the housing 610 in the direction 2101. The sheath 103 andthe insertion tube 119 (FIG. 1 ) of the electrosurgical device 118 maythen be withdrawn from the body. Alternatively, without withdrawing thesheath as described with reference to FIGS. 21A and 21B, once theelectrodes 207 and 211 are withdrawn into the sheath as described withreference to FIGS. 19A-20B, the sheath 103 may be withdrawn from thebody without first withdrawing the sheath 103 by engaging the sheathlock 606.

As previously described with reference to FIGS. 11, 16A, and 17A, thesecondary actuator 1020 supports guide members 1136 and 1138 that engagea helical channel defined by edges of guide sections 1151 and 1153.Referring to FIG. 22 , the guide sections 1151 and 1153 are matedtogether into a guide sleeve 2202 as they are when joined with theprimary actuator 1010. The guide sections 1151 and 1153 may be joined atends 2215 and 2217. Specifically, as shown in FIG. 23 , sockets 2330 maybe supported by the guide sections 1151 and 1153 enabling the guidesections to be connected by screws, dowels, or other fasteners.

Between the ends 2215 and 2217 of the guide sleeve 2202, edges 2211 and2213 of the guide sections 1151 and 1153 define a helical channel 2201.The helical channel 2201 guides the movement of the support members 1136and 1138 to cause the secondary actuator 1020 to translate in responseto rotation of the secondary actuator as described with reference toFIGS. 16A and 17A.

In various embodiments, the generally helical channel 2201 has a variedpitch between the ends 2215 and 2217 of the guide sleeve 2202. Invarious embodiments, the pitch may vary from a rearward end 2215, wherethe secondary actuator 1020 begins its helical movement to extend thesecondary electrode 207, toward a forward end 2217. More specifically,in various embodiments, the pitch of the helical channel is varied toreduce a distance of travel of the secondary actuator 1020 along theaxis 1001 of the user interface 102 (not shown in FIG. 22 ) per unit ofrotation of the secondary actuator 1020 from the rearward end 2215toward the forward end 2217.

In various embodiments, the pitch is varied in this manner to reduce therotational force to be applied by a user in turning the actuator knob1022 to motivate the secondary actuator 1020. For example, consideringFIGS. 5 and 16B, as the distal end 213 of the secondary electrode 211 isadvanced into the target region 202, the distal end 213 of the secondaryelectrode 211 may encounter increased resistance. Part of thisresistance results from the distal end 213 of the secondary electrode211 frictionally engaging a mass in the target region along anincreasing length of the secondary electrode 211 as a longer section ofthe secondary electrode 211 is extended further beyond the distal end209 of the primary electrode 207. Part of this resistance may alsoresult from the curvature of the of the coil at the distal end 213 ofthe secondary electrode 211 encountering an increasing degree ofresistance in augering into the mass at the target region 202.Correspondingly, greater force may be involved at the start ofwithdrawal of the secondary electrode 211 in frictionally engaging agreater mass of tissue than when the secondary electrode 211 is closerto being fully retracted into the distal end 209 of the primaryelectrode 207. Further, when a portion of the secondary electrode 211near the distal end 213 is formed into a coiled shape using a memoryalloy, withdrawing the secondary electrode 207 may involve applicationof additional force in seeking to draw the secondary electrode into adeformed, straightened shape that the secondary electrode 211 assumeswhen confined within the primary electrode 207.

As a result, in deploying the secondary electrode 211, more force may beinvolved in extending the secondary electrode 211 as the secondaryelectrode 211 extends further beyond the distal end 209 of the primaryelectrode 207 into the target region 202. As a result, a greater degreeof rotational force may be involved in rotating the actuator knob 1022of the secondary actuator 1020 as the secondary actuator 1020 movestoward the forward end 2217 of the guide sleeve 2202. Correspondingly,more force may be involved the initial portion of withdrawing thesecondary electrode 211 than when the secondary electrode 211 has beenor nearly has been fully retracted into the primary electrode 207.Therefore, a greater degree of rotational force may be involved inrotating the actuator knob 1022 of the secondary actuator 1020 as thesecondary actuator 1020 first moves away from the forward end 2217 ofthe guide sleeve 2202.

According to various embodiments, the pitch of the helical channel 2201may be varied between the trailing end 2215 and the forward end 2217 ofthe guide sleeve 2202. Specifically, the pitch of the helical channel2201 may be varied to reduce a distance of travel of the second actuator1020 along the axis 1001 per unit of rotation through the curve 1003around the axis 1001 toward the forward end 2217 of the guide sleeve2202 facing a forward end of the user interface 2202. By reducing thedistance of travel of the second actuator 1020 toward the forward end ofthe guide sleeve 2202, the increased force along the axis 1001 iseffectively spread over a greater degree of rotation of the secondactuator 1020. Thus, while lateral resistance to moving the secondaryelectrode 211 along the axis 1001 may increase at a forward end 2217 ofthe guide sleeve 2202, the force involved in rotating the actuator knob1022 to rotate the secondary actuator 1020 does not increase as much.

Referring to FIG. 23 , because the pitch of the helical channel 2201 isdefined by the edges 2211 and 2213 of the guide sections 1151 and 1153,respectively, a pitch of the edges 2211 and 2213 is varied to define ahelical channel 2201 of a desired shape. For example, considering thefirst guide section 1153, at a first point 2301 toward a rearward end2345 of the first guide section 1153, a pitch angle a of the edge 2213(as measured tangentially to the edge 2213 relative to the axis 1001) isgreater than a pitch angle β at a second point 2302 moving toward theforward end 2347 of the first guide section 1153. Similarly, the pitchangle β at the second point 2302 is greater than a pitch angle γ at athird point 2303 moving further toward the forward end 2347 of the guidesection 1153. A corresponding arrangement is repeated with the secondguide section 1151, with a pitch angle along the edge 2211 becoming lessmoving from a rearward end 2341 of the second guide section 1151 towardthe forward end 2343. As a result, despite increased resistance alongthe axis 1001, rotational resistance applied to the secondary actuator1020 is reduced by the decreasing pitch of the helical channel 2201(FIG. 22 ) defined by the decreasing pitch of the edges 2211 and 2213 ofthe respective guide sections 1151 and 1153.

In addition to varying the pitch of the helical channel 2201 tofacilitate deployment and withdrawal of the secondary electrode 207, across-section of the wire used as the secondary electrode 207 also mayease the deployment and withdrawal of the secondary electrode 207.Referring to FIGS. 24-26 , the secondary electrode 207 may include awire having portions 2410 and 2420 of different thicknesses along itslength.

Referring to FIG. 24 , a first portion 2410 of the secondary electrode207 may have a circular cross-section with a first thickness 2412. Asecond portion 2420 leading to the distal end 213 of the secondaryelectrode 211 may have a flat or rectangular cross-section having asecond thickness 2422 that is less than the first thickness 2412. In anillustrative embodiment, the first thickness 2412 of the circularcross-section of the first portion 2410 may be 0.015 inches, and thesecond thickness 2422 of the second portion may be 0.009 inches. In sucha configuration, a theoretical moment of inertia for the first portion2410 is more than twice that of a theoretical moment of inertia for thesecond portion 2420. The greater theoretical moment of inertia of thefirst portion 2410 thus should improve the force transmission of thefirst portion 2410 in advancing the secondary electrode 207 withoutimpeding the capacity of the second portion 2420 to assume its coiledconfiguration upon deployment. The first thickness 24212 is aligned withan axis 2430 that defines a plane in which the second portion 2402 willcoil, as depicted in FIG. 25 .

Referring to FIG. 26 , the secondary electrode 211 is in an uncoiledconfiguration. The second portion 2420 may have a second width 2624 thatis wider than the second thickness 2422 of the second portion 2420 andwider than the first thickness 2412 of the first portion 2410. In anon-limiting example, the first thickness 2412 may be 0.015 inches, thesecond thickness may be 0.009 inches, and the second width may be 0.020inches.

A secondary electrode 211 with the first portion 2410 having a circularcross-section provides good column strength and force transmission formotivating the secondary electrode 211 along its length. The columnstrength and force transmission are helpful in driving the secondaryelectrode 211 through the lumen within the primary electrode 207 and inextending the secondary electrode 211 into a tissue at a target region,as depicted in FIG. 5 . By contrast, with the second portion 2420 havinga reduced thickness in the plane in which the second portion 2420 of thesecondary electrode 211 is to coil makes it easier for the secondaryportion to assume its coiled shape. Using the exemplary dimensions, themoment of inertia of the second portion 2420 is less than half of thatof the first portion 2410, reducing the force required to coil anduncoil the second portion 2410. Having a second width 2624 that islarger than the second thickness 2422 and larger than the firstthickness 2412 improves the column strength and force transmission ofthe second portion 2420 to keep the second portion 2420 from buckling,while still having a thinner second thickness 2422 that facilitates thecoiling of the second portion 2420.

Referring to FIG. 27 , the coupler used to secure the user interface 102with the electrosurgical device 118 includes a slidable mountingmechanism 2710 and a locking body 2720. In various embodiments, theslidable mounting mechanism 2710 is secured to the slidable sleeve 612extending from the housing of the user interface (not shown in FIG. 27 )and fits around the slidable sleeve 612. The slidable sleeve 612 has aninternal width 2791 that is sized to receive a flange 2754 at an end ofa device interface 2752. The flange 2754 has an outer width 2793 that isless than the internal width 2791 of the slidable sleeve 612 so that theflange 2754 is receivable within an end of the slidable sleeve 612. Thedevice interface 2752 has an outer width 2795 that is less than theouter width 2793 of the flange 2754 that it abuts. The outer width 2795of the device interface 2795 and the outer width 2793 of the flange 2754are considered in the configuration of the locking body 2720, as furtherdescribed below with reference to FIG. 28 .

The slidable mounting mechanism 2710 includes a base portion 2712 thatis fixed, fixable, or connected to the slidable sleeve 612 (the slidablemounting mechanism 2710 is shown in FIG. 27 prior to being fixablyconnected to the slidable sleeve 612). The slidable mounting mechanism2710 also includes one or more projections 2714 that are configured toreceive retaining clips 2734 extending from a retaining ring 2730 tosecure the lock plate 2720 to the slidable mounting mechanism 2710, asfurther described below.

The slidable mounting mechanism 2710 also supports a locking pin 2716.In various embodiments, the locking pin 2716 is spring-loaded orotherwise biased to extend outwardly from the slidable mountingmechanism 2710 to engage a locking slot in the locking body 2720 toprevent the locking body 2720 from sliding. The locking pin 2716 may bemanually retracted away from the locking body 2720 to permit the lockingbody 2720 to be moved to an unlocked position.

In various embodiments, the slidable mounting mechanism 2710 includes atorque transfer mechanism to transfer torque between the electrosurgicalinstrument or device 118 (FIG. 1 ) and the user interface 102. Invarious embodiments, the torque transfer mechanism includes a linkage2728 that is received within a channel 2718 when the locking body 2720is in a locked position. The linkage 2728 and the channel 2718 thustransfer torque between the locking body 2720 that is engaged with theelectrosurgical instrument or device 118 and the slidable sleeve 612.The linkage 2718 and channel 2728 thus absorb and/or transfer torquebetween the electrosurgical instrument or device 118 and the slidablesleeve 612, rather than, for example, the torque being exerted on theretaining ring 2730 and/or the locking pin 2716. In various embodiments,torque also may be absorbed and transferred by strengthening the lockingpin 2716 and/or tightening and strengthening the mounting of theretaining ring 2730 to the lock plate 2720.

The locking body 2720 has a base plate 2722 configured to slide acrossthe slidable mounting mechanism 2710 and to hold the flange 2754 inplace within the slidable sleeve 612 to secure the user interface 102 tothe electrosurgical device 118. As further described with reference toFIG. 28 , the base plate 2722 defines an opening havingdifferently-sized sections that alternately permit insertion of theflange 2754 into the slidable sleeve 612 and prevent removal of theflange 2754 from the slidable sleeve 612. The locking body 2720 supportsa hood 2724 that extends over the combination formed by the surgicaldevice interface 2752 with the user interface 102 via the slidablesleeve 612. As previously mentioned, the locking body 2720 also supportsthe second indicator tab 2728. The second indicator tab 2728 aligns withthe first indicator tab 2718 on the slidable mounting mechanism 2710when the locking body 2720 is in a locked position to provide visualconfirmation when the locking body 2720 is in a locked position.

The locking body 2720 is slidably secured to the slidable mountingmechanism with a retainer ring 2730. The retainer ring 2730 includes aring 2732 having an inner diameter 2799 that is sized to receive theflange 2754 extending from the surgical device interface 2752therethrough. Extending from the ring 2732 are one or more retainingclips 2734. The retaining clips 2734 are sized to fit through slots inthe base plate 2722 of the locking body, as further described below withreference to FIG. 28 . Once the retaining clips 2734 are extendedthrough the slots in the base plate 2722 of the locking body 2720, theretaining clips are secured onto and/or around the projections 2714 onthe slidable mounting mechanism 2710. Once the retaining clips 2734 areextended through the slots on the locking body 2720 and secured onto theprojections 2714 on the slidable locking mechanism 2710, the lockingbody 2720 is slidably constrained to move across the slidable mountingmechanism 2710 to lock and unlock the user interface 102 with theelectrosurgical device 118.

Referring to FIG. 28 , the base plate 2722 defines two retaining slots2895 through which the retaining clips 2734 (FIG. 27 ) extend from theretaining ring 2730. The retaining slots 2895 are sized to slidablyreceive the retaining clips 2734 so that the locking body 2720 can slidein a first direction 2815 or a second direction 2817 across theretaining clips 2734. The ring 2732 of the retaining ring 2730 liesacross the base plate 2722 to hold the locking body 2720 to the slidablemounting mechanism 2710 (FIG. 27 ). The locking body 2720 also supportsat least one socket 2820 to receive the locking pin 2716 (FIG. 27 )extending from the slidable locking mechanism 2710. The socket 2820 ispositioned to engage the locking pin 2716 when the locking body 2720 isslid into a locked position over the surgical device interface 2752.

The hood 2724 extends from the locking plate 2722 to cover theconnection between the surgical device interface 2752 and the userinterface 102. To allow the locking body 2720 to move in the seconddirection 2817 without the hood 2724 being blocked by a body of theelectrosurgical device 118 (FIG. 1 ), a lower edge 2825 of the hood 2724is shaped to define a recess 2827. When the locking body 2720 is movedin the second direction 2817 to move the locking body 2720 into a lockedposition, the recess 2827 receives the body of the electrosurgicaldevice 118.

The base plate 2722 of the locking body 2720 defines an opening 2810through which, as described with reference to FIG. 27 , the flange 2754on the surgical device interface 2752 may be inserted into the slidablesleeve 612. More specifically, a first section 2801 of the opening has afirst width 2811 and a conjoined second section 2803 with a second width2813. The first width 2811 of the first section is large enough toreceive the outer width 2793 of the flange 2754 therethrough, while thesecond width 2813 of the second section 2803 is large enough to receivethe width 2795 of the surgical device interface 2752 but not to allowthe outer width 2793 of the flange 2754 to pass therethrough.

To lock the user interface 102 with the electrosurgical device 118 (notshown in FIG. 28 ), the locking body 2720 is slid in the first direction2815 to position the first section 2801 over the opening in the baseportion 2712 of the slidable mounting mechanism 2710 that leads into theslidable sleeve 612 (not shown in FIG. 28 ). The flange 2754 thatextends from the surgical device interface 2752 is then inserted throughthe first section 2801 and into the slidable sleeve 612. To secure thesurgical device interface 2752 in place, the locking body is slid in thesecond direction 2817. As a result, the second section 2803 is movedover the opening in the base portion 2712 of the slidable mountingmechanism 2710, and an edge of the locking body 2722 slides over andabuts the flange 2754. In this locked position, the edge of the lockingplate 2722 around the second section 2803 cover the flange 2754 andholds the flange 2754 in place. Also, with the locking body 2720 in thislocked position, the locking pin 2716 extends into the socket 2820. Thelocking pin 2716 blocks movement of the locking plate in the firstdirection 2815 until the locking pin 2716 is withdrawn from the socket2820.

To uncouple the user interface 102 from the electrosurgical device 118,a user engages the locking pin 2716 to slide it out of the socket 2820to permit sliding movement of the locking body 2720. With the lockingpin 2716 withdrawn, the locking body 2720 is slid in the first direction2815 so that the base plate 2722 moves away from the surgical deviceinterface 2752 with the first section 2801 of the opening 2810 over theflange 2752. The flange 2754 of the surgical device interface 2752 cannow be withdrawn through the locking body 2720, ending the connectionbetween the surgical device interface 2752 and the slidable sleeve 612of the user interface 102.

Referring to FIG. 29 , an illustrative method 2900 of positioningelectrodes for treatment is provided. The method 2900 starts at a block2905. At a block 2910, a distal end of a sheath that contains a primaryelectrode and a secondary electrode is moved adjacent to a targetregion, as described with reference to FIGS. 6A-7B. At a block 2920, aprimary actuator, that is operably coupled with the primary electrodeand a secondary actuator that is operably coupled to the secondaryelectrode and that is movably engaged with the primary actuator, is slidto a first position to motivate distal ends of the primary electrode andthe secondary electrode relative to the target region, as described withreference to FIGS. 14A and 14B. At a block 2930, the secondary actuatoris rotated relative to the primary actuator to cause the secondaryactuator to travel independently of the primary actuator along a helicalpath to a second position to motivate the distal end of the secondaryelectrode to move independently of the primary electrode relative to thetarget region, as previously described with reference to FIGS. 16A and16B. The method 2900 ends at a block 2935, with the electrodes nowpositioned.

Referring to FIG. 30 , an illustrative method 3000 of motivating animplement through a helical path having a varied pitch is provided. Themethod 3000 starts at a block 3005. At a block 3010, an elongatedimplement is coupled at a proximal end thereof to an actuator that ismovable along an axis, as described with reference to FIG. 11 . At ablock 3020, the implement is motivated by rotatably moving the actuatorthrough a generally helical path around the axis, the helical pathhaving a pitch that is varied to change a distance traveled by theactuator along the axis per unit of rotation of the actuator, asdescribed with reference to FIGS. 16A, 16B, 22, and 23 . The method 3000ends at a block 3025, with the actuator having moved the implement.

Referring to FIG. 31 , an illustrative method 3100 of securing devicestogether is provided. The method 3100 starts at a block 3105. At a block3110, a locking body is positioned into an open position, where thelocking body defines an opening with a first section having a firstwidth and a second section having a second width that is smaller thanthe first width. The locking body is slidably mounted on one of a firstdevice that supports a first coupling and a second device that supportsa second coupling. The first section is disposed between the firstcoupling and the second coupling when the locking body is positionedinto the open position, as described with reference to FIG. 28 . At ablock 3120, a connection is formed by inserting the first couplingwithin the second coupling where one of the first and second couplingssupports a flange having a flange width that is smaller than the firstwidth and larger than the second width, as described with reference toFIG. 28 . At a block 3130, the locking body is repositioned into aclosed position in which an edge of the locking body around the secondsection abuts the flange so that the coupling that supports the flangeis prevented from being withdrawn from the connection, as previouslydescribed with reference to FIG. 28 . The method 3100 ends at a block3135, with the couplings secured together by the locking body.

It will be appreciated that the detailed description set forth above ismerely illustrative in nature and variations that do not depart from thegist and/or spirit of the claimed subject matter are intended to bewithin the scope of the claims. Such variations are not to be regardedas a departure from the spirit and scope of the claimed subject matter.

What is claimed is:
 1. An apparatus comprising: an elongated implementmovable along an axis; a rotatable actuator operably coupled with aproximal end of the implement to motivate the implement to move alongthe axis in response to rotation of the rotatable actuator; and a guideoperably coupled with rotatable actuator, wherein the guide defines agenerally helical channel around the axis to direct movement of arotatable actuator, and wherein a pitch of the helical channel is variedalong a length of the guide to reduce an axial distance of travel of theactuator along the axis per unit of rotation of the rotatable actuatoras the rotatable actuator travels distally relative to the guide,wherein the pitch is varied to reduce a distance traveled by thesecondary actuator along the axis per unit of rotation of the secondaryactuator at a position at which the secondary electrode is anticipatedto exert an increased resistance on the secondary actuator to movementalong the axis, and wherein the pitch of the helical channel is variedto increase the movement of the secondary actuator along the axis at asecond position where the secondary electrode is anticipated to exert areduced resistance on the secondary actuator to movement along the axis.2. The apparatus of claim 1, wherein the position at which the implementis anticipated to exert the increased resistance corresponds to alocation at which movement of a distal end of the implement is expectedto be impeded by an obstruction.
 3. The apparatus of claim 1, whereinthe position at which the implement is anticipated to exert theincreased resistance corresponds to a location at which a configurationof a distal portion of the implement resists movement of the implement.4. The apparatus of claim 3, wherein the configuration of the distalportion of the implement that resists movement of the implement includesthe distal portion of the implement formable into a coiled shape at anend of a lumen through which the implement is extended, such that atleast one of coiling into the coiled shape upon extending from the lumenand uncoiling from the coiled shape upon being retracted into the lumenresults in an increased resistance to movement of the implement alongthe axis.
 5. The apparatus of claim 1, wherein the guide includes anannular tube that defines the helical channel.
 6. The apparatus of claim5, wherein the rotatable actuator is receivable within the annular tube.7. The apparatus of claim 6, wherein the annular tube includes twomatable sections configured to be disposed around the rotatableactuator, wherein opposing distal edges of the two matable sectionscomprise edges of the helical channel.
 8. A system comprising: anelongated primary electrode defining a lumen therein; an elongatedsecondary electrode slidably receivable within the lumen; a sheathconfigured to slidably receive the primary electrode therein, the sheathbeing further configured to convey the primary electrode and thesecondary electrode toward a target region; a housing operably coupledwith the sheath and movably mounted to slidably motivate the sheathrelative to the target region; a primary actuator operably coupled withthe primary electrode and slidably coupled with the housing to motivatethe primary electrode to slide relative to the sheath along an axis andincluding a guide defining a generally helical channel; a secondaryactuator operably coupled with the secondary electrode and rotatablyreceived within the guide of the primary actuator, wherein the secondaryactuator supports a guide member that is configured to engage thehelical channel, and wherein the secondary actuator is rotatablerelative to the primary actuator to motivate the secondary electrode tomove relative to the primary electrode, wherein a pitch of the helicalchannel is varied along a length of the guide to reduce axial movementof a guide member relative to the axis per unit of rotation of thesecondary actuator around the helical channel as the secondary actuatortravels distally relative to the primary actuator, wherein the pitch isvaried to reduce a distance traveled by the secondary actuator along theaxis per unit of rotation of the secondary actuator at a position atwhich the secondary electrode is anticipated to exert an increasedresistance on the secondary actuator to movement along the axis, andwherein the position at which the secondary electrode is anticipated toexert the increased resistance corresponds to a location at whichmovement of a distal end of the distal end is expected to be impeded byan obstruction.
 9. The system of claim 8, wherein the position at whichthe secondary electrode is anticipated to exert the increased resistancecorresponds to a location at which a configuration of a distal portionof the secondary electrode resists movement of the secondary electrode.10. The system of claim 9, wherein the configuration of the distalportion of the secondary electrode that resists movement of thesecondary electrode includes the distal portion of the secondaryelectrode forming a coiled shape at an end of the lumen, wherein atleast one of coiling into the coiled shape upon extending from the lumenand uncoiling from the coiled shape upon being retracted into the lumenresults in an increased resistance to movement of the secondaryelectrode along the axis.
 11. The system of claim 8, wherein the pitchof the helical channel is varied to increase the movement of thesecondary actuator along the axis at a second position where thesecondary electrode is anticipated to exert a reduced resistance on thesecondary actuator to movement along the axis.
 12. The system of claim8, wherein the guide includes an annular tube that defines the helicalchannel.
 13. A method comprising: coupling an elongated implement at aproximal end thereof to an actuator that is movable along an axis; andmotivating the implement by rotatably moving the actuator in referenceto a guide through a generally helical path around the axiscreated bythe guide, the helical path having a pitch that is varied along a lengthof the guide to change a distance traveled by the actuator along theaxis per unit of rotation of the actuator as the actuator travelsdistally relative to the guide, wherein the pitch is varied to reduce adistance traveled by the actuator along the axis per unit of rotation ofthe actuator at a position at which the implement is anticipated toexert an increased resistance on the actuator to movement along theaxis, and wherein the position at which the elongated implement isanticipated to exert the increased resistance corresponds to a locationat which a configuration of a distal portion of the implement resistsmovement of the implement.
 14. The method of claim 13, wherein theposition at which the elongated implement is anticipated to exert theincreased resistance corresponds to a location at which movement of adistal end of the implement is expected to be impeded by an obstruction.